Dynamo electric machine



Jan. 20, 1959 J. E. ANTONIDIS ET AL DYNAMO ELECTRIC MACHINE Filed April 2, 1956 mmmM M 3? \M FZ w R h N /W ,4 Hg 5 0 Unite States Patent f 1 2,870,354 DYNAMO ELECTRIC MACHINE John E. Antonidis, Anderson, Merrill E. Dray, Marion,

and Robert A. Ulm, Anderson, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April 2, 1956, Serial No. 575,631 6 Claims. (Cl. 310-247) This invention relates to brushes and brush holders for dynamoelectric machines and more particularly to an improved brush holder and the connection between the terminal lead and the brush which is held in position by the brush holder.

It is an object of the present invention to provide an economical brush holder for a dynamoelectric machine, with a minimum of inexpensive parts; and to form these parts to receive the end of the brush that has the end of the terminal lead wire weld directly thereto.

A further object of the present invention is to form a connection between the end of a stranded wire pigtail and a brush that is formed of a plurality of wire strands. This object is achieved by welding the end of the stranded wire pigtail to the ends and not the sides of the wire strands which form a major portion of the brush structure.

Another object of the present invention is to form a brush holder of a pair of bent metal strips one of which pair is provided with a curved surface so it can be secured to the inner surface of a tubular dynamoelectric unit and the other of which is formed and secured to the first of the pair to define an open ended chamber wherein a coiled spring is positioned and held by means on both of said strips.

A'still further object of the present invention is to connect all of the parts of a brush holder and the pigtail and brush by welding so as to considerably reduce the cost of manufacture of a brush holder assembly. This object is accomplished by forming and welding two metal parts together to form a chamber and by welding one end of the pigtail directly to the end of the brush which is formed of metal strands which are disbursed in the body of the brush and by welding the other end of the pigtail to one of the metal parts of the holder.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

Figure 1 is a side view of a dynamoelectric unit having a portion of the exterior broken away to show the brush 'andbrush holder according to the present invention.

Figure 2 is a sectional view through the unit in Figure 1 showing how the brush and brush holders are mounted.

Figure 3 is a plan and side view of one of the formed metal strip parts which form a part of the brush holder.

Figure 4 is a plan and side view of another of the formed metal strip parts which forms another part of the brush holder.

Figure 5 is a view of a spring as used in the brush holder.

Figure 6 is a sectional view of a brush showing the welded connection between the wire strands which form the lead wire and the ends of the wire strands in the brush.

- In the drawings and in Figures 1 and 2 particularly, the brush holder 20 is shown as mounted in a dynamoelectric unit 22. The unit 22 shown is of the conventional type and includes a shaft which carries and rotates a commutator 24. The commutator 24 is formed of a plurality of segments which may be replaced by slip rings,

Patented Jan. 20, 1959 if desired, as the brush holder 20 and the brush 26, shown in Figure 6, may be used with either alternating or direct current dynarnoelectric units.

The brush holder 20 is formed from metal parts shown in Figures 3 to 5. The brush holder part 28 in Figure 3 is formed of a single strip of metal. This part 28 has a flat wall portion 30 and an arcuately curved wall portion 32 which is disposed at right angles to the flat wall portion 30. The curve of the arcuate wall 32 may be of the same radius as the radius of the inner surface of the unit 22 so the brush holder may be suitably secured within the unit 22, by rivets 34. These rivets 34 pass through holes 36 in the arcuate wall. If desired, the brush holder may be electrically insulated from or be in electrical contact with the tubular frame of the unit 22 as shown, respectively, in the upper and lower brush holders in Figure 2. When the latter arrangement is used, the pigtail 38 from brush 26, which will be hereinafter described, is generally welded directly to the brush holder 20. The brush holder part 42 is also formed of a bent strip of metal as shown in Figure 4. The part 42 has a pair of spaced walls 44 and 46 which are interconnected by a curved web portion 48. Extending in opposite directions from the spaced walls 44 and 46 are a pair of flanges 50 and 52, respectively. These flanges 50 and 52 each may have locating pimples which are received in locating holes 54 in the fiat wall 30 of part 28 to aid in the positioning of parts 28 and 42 when the parts 23 and 42 are welded together with the bottom edge of the part 42 juxtaposed but spaced from the arcuately curved portion 32 of member 28 (see Figure 2).

In Figure 4, it will be seen that the spaced Walls 44 and 46 are formed with outwardly curved portions 54 and 56, respectively. The portions 54 and 56 extend over the entire width of the strip member and aid in defining a space or chamber wherein the brush spring 58 is received. In Figure 3, the curved portion 32 of member 28 is shown as having a projection 60. This projection 60 is formed by stretching the metal of the arcuate portion 32 to form a raised portion or projection 60 which will extend into the inner space of the coil spring 58 which also helps position the spring 58 properly in the chamber defined by portions 54 and 56. The curved portions 54 and 56 are partially cut out to form slots or notches 62 and 64. These slots 62 and 64 preferably extend from the edge 41 of member 42 and terminate in a rounded base spaced from the edge 43 of the member 42. The edges of the slots 62 and 64 are preferably outwardly rounded as shown by the numeral 66 to provide a smooth edge for the walls of the slots 62 and 64. This rounded edge 66 will prevent chafing of the terminal lead or pigtail 38 which will be hereinafter more fully described. Located along the top edges of member 42 and extending into slots 62 and 64 from the opposite edges thereof are four spaced lugs 70. These lugs will help maintain the spring 58 under a suitable initial compression on the arcuately curved portion 32 ofmember 28 and Within the space defined by curved portions 54 and 56. The lugs 70'are preferably formed to have downwardly inclined edges 71 along the top of member 42. This will permit the spring to be readily inserted into position.

In Figure 6 of the drawings, a metallic type brush 26 is shown. This brush may be formed according to the teachings set forth in U. S. Patent 1,198,873, which has been assigned by the inventor to the assignee ofthe present invention. This brush is preferably formed of a plurality of conducting metal strands, i. e., copper, which are promiscuously dispersed throughout the brush body and which strands are held in position by a mixture of carbon and a binder so the strands are oriented subasrosse 3 stantially parallel to the major axis of the brush, or, in otherwords, so the strands are perpendicularly disposed to the edge 72. The end of the stranded wire terminal lead or pigta'il 38 is welded in this position, a firm arid highly satisfactory welded connection is established as the individual strands of the pigtail are welded to the exposed ends of the strands 7 5 of the brush. This is a rather unusual result in that when the pigtail is welded to the sides of the brush, an unsatisfactory connection is established. It is believed this result can be best explained asfollows. When the pigtail is welded to end 72, then the welded connection is formed with the end surfaces of the strands which form a portion of the brush. These strands, becausethey are perpendicular to the end '72, are securely embedded in the brush body and will not be pulled loose when stress is applied on the welded connection. on the other hand, when the pigtail is welded to the side or" the brush, then the individual s ands will be pulled loose and the connection is easily broken.

After the welded connection between the pigtail 38 and brush 26 is established as indicated, the brush is inserted into the space 74, defined by the spaced walls 44 and 46, the curved connecting web 4-8, and the portion ofmember 28 between the spaced walls 44 and 4-6. When the brush is inserted into this space 74, the spring 55 will urge the brush into engagement with the commutator of the dynamoelectric unit (see Figure 2). Further, the pigtail will extend through one of the slots 52 and 64 and, thus, permit free movement of the brush in space 74. The strands of the pigtail will not be damaged or chafed when the pigtail moves in these slots as the turned out edges as present a smooth surface on which the pigtails may ride.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed isas follows:

l. A brush holder for holding a brush in contact with a commutator in a dynamoelectric machine having a tubular frame, comprising; an L-shaped member having a llat wall and an arcuately curved wall portion at right angles to the flat wall, a strip member having a pair of spaced Walls, a curved web interconnecting the spaced walls and a pair of flanges oppositely extending fro said spaced walls secured to said fiat wall so one edge of said strip member is juxtaposed to the curved portion of said L-shaped member, a raised portion in said curved wall extending centrally between the spaced walls, a pair of siots in each of said spaced walls, extending in said spaced walls from an open end to a closed end adjacent the curved portion of said L-shaped member, a spring disposed between said spaced walls and positioned by said raised portion, 2. lug adjacent the open ends of said slots for maintaining said spring between said spaced walls, and. a brush sized to be received between said spaced walls and having an end engageable with said spring, said brush having a portion thereof comprising a quantity of time metallic strands promiscuously disposed throughout said brush with the strands being oriented substantially parallel with the brushs major axis, and a pigtail welded to the end of said brush that is in engagement with said spring.

2. The combination of a commutator brush consisting essentially of a plurality of fine metallic strands wherein said strands are promiscuously disposed throughout a mixture of carbon and a binder and wherein the strands are oriented substantially perpendicular to an end of said brush, and a braided metal wire terminal lead for said brush wherein the lead has one of its ends welded to said end of said brush.

3. A brush holder for use in a dynamoelectric machine having a tubular frame comprising; a pair of bent metal strips connected to define a chamber with a curved flange on one of said strips arranged to be secured to an inner surface of said frame and the other strip has a pair of open ended slots therein, a coiled spring within said chamber having one end thereof engageable with the inner side of said curved flange, and shoulder means on both of said strips engageable with said spring for maintaining said spring in position within said chamber.

4. In a method for attaching an end of a stranded metal wire terminal lead to a brush that includes a plurality of fine metal wire strands held together by a mixture of carbon and a binder and which are oriented substantially perpendicular to an end of said brush, the step of weld ing the endof the lead directly to the ends only of the metal strands.

5. A brush holder for holding a brush in contact with a commutator in a dynamoelectric machine having a tubular frame comprising; an L-shaped member having a flat wall portion and an arcuately curved wall portion disposed at right angles to the flat wall portion securable to an inner wall portion of said tubular frame, a strip member having a pair of spaced walls interconnected with a curved web portion and having a pair of flange portions oppositely extending from the spaced walls, said flange portions being secured to said fiat portion with one edge of said strip member juxtaposed to the curved portion of said L-shaped member, said curved web portion, said spaced walls, a portion of the flat wall portion and a portionof said curved wall portion cooperating with each other to define a chamber with an open end, a raised portion in said curved wall extending into said chamber, a curved portion in each of said spaced walls forming an enlargement in said chamber, a spring within said chamber positioned by said raised portion and the curved portions in said spaced walls, a pair of slots in the curved portions of said spaced Walls extending from the open end of said chamber toward said arcuately curved wall and lugs adjacent the open end of said slots for maintaining said spring in said chamber.

6. A brush holding arrangement for a dynamoelectric machine of the type having a tubular frame comprising, a metal member having an arcuately extending portion attached to an arcuately extending inner wall portion of said tubular frame, first, second and third sheet metal walls extending radially from said arcuately extending portion with said first and second walls being joined together at the end thereof opposite the arcuately extending portion by a curved web, said first, second and third walls and said web defining a substantially rectangular brush holder chamber having one end closed by said arcuately extending portion, a radially extending slot formed in each of said first and second walls, a brush in said chamber having a lead wire attached thereto that passes through one of said slots and whose configuration conforms to the configuration of said chamber, a coiled compression spring located within said chamber and positioned between said brush and said arcuately extending portion for urging said brush outwardly of said brush holding chamber, and means extending radially from 'said arcuately extending portion for positioning one end of said spring in said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 677,348 Fish July 2, 1961 1,396,948 Cooley Nov. 15, 1921 1,509,666 Campbell Sept. 23, 1924 1,707,317 Pipes Apr. 2, I929 1,835,011 Burr Dec, 8, 1931 2,361,378 Brennan Get. 31, 1944 2,584,214 Luther Feb. 5, 1952 2,629,061 'Swarthout Feb. 17, 1953 2,710,360 Dennis June 7, 1955 2,760,094 Edmundson Aug. 21, 1956 FOREIGN PATENTS 243,204' Switzerland Dec. 2, 1946 

